Red Velvet’s Seulgi and Sunmi Write Touching Letters To Each Other Following Their Newfound Friendship

These not-so-secret unnie & dongsaeng couple is sisterhood goals!

The TV program Secret Unnie has helped several female K-Pop idols find fellow female celebrities, creating some of the strongest sisterhoods in the industry. It seems the latest “Unnie (언니, older sister)” and “Dongsaeng (동생, younger sibling)” couple is Sunmi and Red Velvet‘s Seulgi!


After seven episodes together, Sunmi and Seulgi grew extremely close. For their last shoot, the two idols wrote letters to each other. The show’s official Instagram account shared these handwritten letters that are the beginnings of what is about to be K-Pop’s most visually beautiful sisterhood.

A post shared by 비밀언니 (@secret_unnie) on


Seulgi explained, “I didn’t write it like this was the last time I’m going to see her, because I’m going to see her again.” 

“Dear Sunmi Unnie,
This is kind of embarrassing… lol. When I first saw you, I was only 14 and dreaming of becoming a celebrity. Now that we’re working in the same industry and we’ve met through this show, I’m extremely grateful. It meant so much to me to get to know you better! Whenever I saw you at studios, I thought you’re amazing but I could never approach you. So when you opened up to me first and called me your “dongsaeng”, I fell even more in love with you – not only as an artist but as a person. I loved listening to you talk. Everything you told me will help me greatly in the future. I hope our friendship doesn’t end here and I look forward to being like a real sister to you. Thank you so much for the wonderful two days!” — Seulgi


Sunmi was thrilled to have gotten to know Seulgi, as she “always wanted a younger sister.” 

“Seulgi, you still remind me of the color blue when I see you LOL. I don’t think I have anything left unsaid, and I know that we’re going to keep in touch haha, but since this is the mission, here I go. Thank you so much for becoming my little sister. I feel like I found myself another best friend. Time went by so quickly, so I have a lot of things I want to try with you. Hehe. I look forward to us becoming really close friends. My secret dongsaeng Seulgi! Just keep doing what you’ve been doing, yeah! Haha. To my Seulgi, from your secret unnie.” — Sunmi


It isn’t just Sunmi and Seulgi who look forward to the newfound friendship / sisterhood. Fans are going wild for the sisterly chemistry that these two idols had with each other!


Watch the last episode where Seulgi and Sunmi’s friendship really begins to shine: